Thailand has declared martial law in three southern Muslim provinces after two days of arson attacks and bombings. Prime Minister Thaksin Shinawatra is blaming Islamic separatists for the violence.

The Thai government moved to restore order by declaring martial law in the mostly Muslim provinces of Narathiwat, Yala and Pattani.

Attackers have set fire to 21 schools, raided an army depot for weapons, and planted four bombs. At least six people have been killed since Sunday.

Prime Minister Thaksin Shinawatra blamed the attacks on Muslim insurgents collaborating with what he called "insiders." He singled out his interior minister, Wan Muhamad Nor Matha, a Muslim responsible for police and security, for failing to be aware that trouble was brewing.

Buddhist Thailand experienced a Muslim insurgency in the south, until reconciliation efforts by the government in the 1980s.

But violence has erupted in the past two years, with more than 50 police and soldiers perishing in attacks.

Analysts say the violence is not directly linked to a separatist movement, but is more likely the work of former Muslim insurgents who have turned to gunrunning and banditry.

Peerayot Rohimmula, a political scientist with the Prince of Songklah University in Southern Thailand, says there may be some collusion between corrupt officials and the former Islamic insurgents he refers to as Mujahedin.

"The Mujahedin [Islamic fighters] that exists in the Southern Thailand now is not the real Mujahedin - [but] the group of ordinary criminals [and] some government officers stand behind this group to do something for their interests," he said.

Mr. Peerayot says he is concerned that martial law, implemented to fight what is essentially crime, will hurt investment and tourism, both vital for the local economy.

Mr. Thaksin says the government had been reluctant to impose martial law, which allows the military to search homes and detain suspects without charge.